1. Technical Field
The invention relates to processor technologies, and more particularly to a processor, a processor system, a temperature estimation device, an information processing apparatus, and a temperature estimation method capable of estimating the temperature inside the processor.
2. Related Art
With increasing trends of LSI design toward finer manufacturing processes and higher device integration, it is becoming extremely important, in terms of design, to give consideration to the amount of heat generation as chips' performance limits. Chips can malfunction or drop in long-term reliability when at high temperatures. Various measures against heat generation have thus been taken. For example, in one method, radiating fins are arranged on the top of a chip so as to radiate heat occurring from the chip.
Moreover, uneven distribution of power consumption over a chip inevitably produces the problem of so-called “hot spots,” or that the chip partially becomes abnormally high in temperature. Then, it has also been studied to schedule processor tasks based on the distribution of power consumption of a chip (for example, see U.S. Patent Application Publication No. 2002/0065049).
When heat occurs from part of a chip, the high-temperature area spreads out from the location of heat generation with time because of heat conduction, and the entire chip eventually rises in temperature. Conventional measures against heat generation are to embed only a single temperature sensor into a device such as a processor to measure the temperature inside the device, observe the temperature distribution on the entire chip macroscopically, and radiate heat over time of several seconds to a minute or so. This means poor time response. Among latest highly-integrated LSIs are ones that are designed to consume power of around several tens of watts each. Heat radiation processing must therefore be conducted in the order of several tens of microseconds, or a malfunction can occur due to an abrupt rise in temperature.
Powerful cooling mechanisms using a heat sink or the like are thus provided to lower the temperature sharply under circumstances where the power consumption is growing. This increases the heat flux flowing into the heat sink relatively, thereby causing the phenomenon that the heat flux to spread over the chip surface decreases. The small heat resistance to the heat sink formed on the top of the chip can be regarded as an equivalent to a relative drop in the heat conductivity of the chip. In this state, local hot spots can occur easily. As above, since highly-integrated processors cause a plurality of hot spots in places, it has been difficult to grasp the temperatures of the hot spots with a single temperature sensor accurately.